Habitat: Eurasia; this species is predominantly migratory and travels over land making brief stop overs. It breeds from mid-May in solitary pairs with well-defined territories; non-breeders remaining in flocks separate from breeding pairs. Adults undergo a post-breeding molt period between late-July and early-August when they become flightless for 30 days, males starting to molt before the females. Non-breeding individuals molt at the same time as breeders, but while breeding pairs tend to molt in their breeding territories, non-breeders molt in large congregations. After molting, the species begins to migrate south from late-September to October determined by weather conditions and arrives on the wintering grounds by October or November. The species departs for the breeding grounds again from March to April or early-May. Outside of the breeding season the species is highly sociable, migrating in small flocks or family groups and congregating into flocks of up to 300-400 individuals in the winter. The species roosts on areas of open water adjacent to its feeding areas. The Whooper Swan is a rare migrant to North America.

The Whooper Swan breeds on islands in or along the banks of shallow freshwater pools, lakes, slow-flowing rivers, marshes, swamps and bogs. They show a preference for habitats with abundant emergent vegetation and reed beds in coniferous forest zones, birch forest zones and shrub/forest tundra (generally avoiding open areas). Non-breeders may also be found in flocks along sheltered coasts on estuaries, lagoons and shallow bays during this season.

On migration, the species frequents lakes, estuaries and sheltered coasts. It traditionally winters on freshwater lakes and marshes, flood plains, brackish lagoons and coastal bays, although low-lying coastal agricultural land and wet pastures are now used increasingly.

Status: Least Concern. Global population: 180,000 adult individuals. The overall population trend is uncertain, as some populations are decreasing, while others are increasing, stable or have unknown trends.

The species is threatened by habitat degradation and loss (such as the reclamation of coastal and inland wetlands) especially in the Asian part of its breeding. Threats to its habitats include agricultural expansion, wetland drainage for irrigation, overgrazing by livestock (e.g. sheep), vegetation cutting for winter livestock feed, the development of roads, mining (e.g. strip mining of sediment), hydroelectric dam construction, disturbance from tourism and chronic oil pollution from oil exploration, exploitation and transportation.

It is listed under the Agreement on the Conservation of African-Eurasian Migratory Waterbirds (AEWA).

Diet: Herbivorous; its diet consisting of the leaves, stems and roots of aquatic plants such as algae and Zostera, Ruppia and Potamogeton spp., grasses, sedges and horsetails (Equisetum spp.). During the winter the species also takes agricultural grain, vegetables such as potatoes and turnips and acorns. On the breeding grounds, young birds often take adult and larval insects. Adults may also supplement their diet with marine and freshwater mussels.

The whooper swan spends much of its time swimming, straining the water for food, or eating plants that grow on the bottom. This species has upright posture and generally swims with a straight neck.

Nesting: Sexes are alike. The Whooper Swan is similar in appearance to the Bewick's Swan, but larger. It has a more angular head shape and a more variable bill pattern that always shows more yellow than black (Bewick's Swans have more black than yellow).

Whooper Swans pair for life, and their cygnets stay with them all winter; they are sometimes joined by offspring from previous years. Their preferred breeding habitat is wetland, but semi-domesticated birds will build a nest anywhere close to water. The pair helps equally in building the nest. The female will usually lay 4–7 eggs and the male will stand guard over the nest while the female incubates. The cygnets hatch after about 36 days and have a grey or brown plumage. The cygnets can fly at an age of 120 to 150 days.

Cool Facts: Its common name refers to the loud 'whooping' calls that it produces. Whooper Swans require large areas of water to live in, especially when they are still growing, because their body weight cannot be supported by their legs for extended periods of time.

The musical call made by Whooper Swans at the moment of death is believed to be the origin of the “swan song” phrase.

The Whooper Swan is the national bird of Finland and is featured on the Finnish 1 euro coin.